<?php

/**
 * Copyright 2011 Facebook, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License. You may obtain
 * a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
if (!function_exists('curl_init'))
{
    throw new Exception('Facebook needs the CURL PHP extension.');
}

if (!function_exists('json_decode'))
{
    throw new Exception('Facebook needs the JSON PHP extension.');
}

/**
 * Thrown when an API call returns an exception.
 *
 * @author Naitik Shah <naitik@facebook.com>
 */
if (!class_exists("YNSFacebookApiException"))
{

    class YNSFacebookApiException extends Exception
    {

        /**
         * The result from the API server that represents the exception information.
         */
        protected $result;

        /**
         * Make a new API Exception with the given result.
         *
         * @param array $result The result from the API server
         */
        public function __construct($result)
        {
            $this->result = $result;

            $code = isset($result['error_code']) ? $result['error_code'] : 0;

            if (isset($result['error_description']))
            {
                // OAuth 2.0 Draft 10 style
                $msg = $result['error_description'];
            }
            else if (isset($result['error']) && is_array($result['error']))
            {
                // OAuth 2.0 Draft 00 style
                $msg = $result['error']['message'];
            }
            else if (isset($result['error_msg']))
            {
                // Rest server style
                $msg = $result['error_msg'];
            }
            else
            {
                $msg = 'Unknown Error. Check getResult()';
            }

            parent::__construct($msg, $code);
        }

        /**
         * Return the associated result object returned by the API server.
         *
         * @return array The result from the API server
         */
        public function getResult()
        {
            return $this->result;
        }

        /**
         * Returns the associated type for the error. This will default to
         * 'Exception' when a type is not available.
         *
         * @return string
         */
        public function getType()
        {
            if (isset($this->result['error']))
            {
                $error = $this->result['error'];
                if (is_string($error))
                {
                    // OAuth 2.0 Draft 10 style
                    return $error;
                }
                else if (is_array($error))
                {
                    // OAuth 2.0 Draft 00 style
                    if (isset($error['type']))
                    {
                        return $error['type'];
                    }
                }
            }

            return 'Exception';
        }

        /**
         * To make debugging easier.
         *
         * @return string The string representation of the error
         */
        public function __toString()
        {
            $str = $this->getType() . ': ';
            if ($this->code != 0)
            {
                $str .= $this->code . ': ';
            }
            return $str . $this->message;
        }

    }

}

/**
 * Provides access to the Facebook Platform.  This class provides
 * a majority of the functionality needed, but the class is abstract
 * because it is designed to be sub-classed.  The subclass must
 * implement the four abstract methods listed at the bottom of
 * the file.
 *
 * @author Naitik Shah <naitik@facebook.com>
 */
if (!class_exists("YNSBaseFacebook"))
{

    abstract class YNSBaseFacebook
    {
        /**
         * Version.
         */

        const VERSION = '3.2.0';

        /**
         * Signed Request Algorithm.
         */
        const SIGNED_REQUEST_ALGORITHM = 'HMAC-SHA256';

        /**
         * Default options for curl.
         */
        public static $CURL_OPTS = array(
            CURLOPT_CONNECTTIMEOUT => 10,
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_TIMEOUT => 60,
            CURLOPT_USERAGENT => 'facebook-php-3.2',
        );

        /**
         * List of query parameters that get automatically dropped when rebuilding
         * the current URL.
         */
        protected static $DROP_QUERY_PARAMS = array(
            'code',
            'state',
            'signed_request',
        );

        /**
         * Maps aliases to Facebook domains.
         */
        public static $DOMAIN_MAP = array(
            'api' => 'https://api.facebook.com/',
            'api_video' => 'https://api-video.facebook.com/',
            'api_read' => 'https://api-read.facebook.com/',
            'graph' => 'https://graph.facebook.com/',
            'graph_video' => 'https://graph-video.facebook.com/',
            'www' => 'https://www.facebook.com/',
        );

        /**
         * The Application ID.
         *
         * @var string
         */
        protected $appId;

        /**
         * The Application App Secret.
         *
         * @var string
         */
        protected $appSecret;

        /**
         * The ID of the Facebook user, or 0 if the user is logged out.
         *
         * @var integer
         */
        protected $user;

        /**
         * The data from the signed_request token.
         */
        protected $signedRequest;

        /**
         * A CSRF state variable to assist in the defense against CSRF attacks.
         */
        protected $state;

        /**
         * The OAuth access token received in exchange for a valid authorization
         * code.  null means the access token has yet to be determined.
         *
         * @var string
         */
        protected $accessToken = null;

        /**
         * Indicates if the CURL based @ syntax for file uploads is enabled.
         *
         * @var boolean
         */
        protected $fileUploadSupport = false;

        /**
         * Indicates if we trust HTTP_X_FORWARDED_* headers.
         *
         * @var boolean
         */
        protected $trustForwarded = false;

        /**
         * Initialize a Facebook Application.
         *
         * The configuration:
         * - appId: the application ID
         * - secret: the application secret
         * - fileUpload: (optional) boolean indicating if file uploads are enabled
         *
         * @param array $config The application configuration
         */
        public function __construct($config)
        {
            $this->setAppId($config['appId']);
            $this->setAppSecret($config['secret']);
            if (isset($config['fileUpload']))
            {
                $this->setFileUploadSupport($config['fileUpload']);
            }
            if (isset($config['trustForwarded']) && $config['trustForwarded'])
            {
                $this->trustForwarded = true;
            }
            $state = $this->getPersistentData('state');
            if (!empty($state))
            {
                $this->state = $state;
            }
        }

        /**
         * Set the Application ID.
         *
         * @param string $appId The Application ID
         * @return YNSBaseFacebook
         */
        public function setAppId($appId)
        {
            $this->appId = $appId;
            return $this;
        }

        /**
         * Get the Application ID.
         *
         * @return string the Application ID
         */
        public function getAppId()
        {
            return $this->appId;
        }

        /**
         * Set the App Secret.
         *
         * @param string $apiSecret The App Secret
         * @return YNSBaseFacebook
         * @deprecated
         */
        public function setApiSecret($apiSecret)
        {
            $this->setAppSecret($apiSecret);
            return $this;
        }

        /**
         * Set the App Secret.
         *
         * @param string $appSecret The App Secret
         * @return YNSBaseFacebook
         */
        public function setAppSecret($appSecret)
        {
            $this->appSecret = $appSecret;
            return $this;
        }

        /**
         * Get the App Secret.
         *
         * @return string the App Secret
         * @deprecated
         */
        public function getApiSecret()
        {
            return $this->getAppSecret();
        }

        /**
         * Get the App Secret.
         *
         * @return string the App Secret
         */
        public function getAppSecret()
        {
            return $this->appSecret;
        }

        /**
         * Set the file upload support status.
         *
         * @param boolean $fileUploadSupport The file upload support status.
         * @return YNSBaseFacebook
         */
        public function setFileUploadSupport($fileUploadSupport)
        {
            $this->fileUploadSupport = $fileUploadSupport;
            return $this;
        }

        /**
         * Get the file upload support status.
         *
         * @return boolean true if and only if the server supports file upload.
         */
        public function getFileUploadSupport()
        {
            return $this->fileUploadSupport;
        }

        /**
         * DEPRECATED! Please use getFileUploadSupport instead.
         *
         * Get the file upload support status.
         *
         * @return boolean true if and only if the server supports file upload.
         */
        public function useFileUploadSupport()
        {
            return $this->getFileUploadSupport();
        }

        /**
         * Sets the access token for api calls.  Use this if you get
         * your access token by other means and just want the SDK
         * to use it.
         *
         * @param string $access_token an access token.
         * @return YNSBaseFacebook
         */
        public function setAccessToken($access_token)
        {
            $this->accessToken = $access_token;
            return $this;
        }

        /**
         * Extend an access token, while removing the short-lived token that might
         * have been generated via client-side flow. Thanks to http://bit.ly/b0Pt0H
         * for the workaround.
         */
        public function setExtendedAccessToken()
        {
            try
            {
                // need to circumvent json_decode by calling _oauthRequest
                // directly, since response isn't JSON format.
                $access_token_response = $this->_oauthRequest(
                        $this->getUrl('graph', '/oauth/access_token'), $params = array(
                    'client_id' => $this->getAppId(),
                    'client_secret' => $this->getAppSecret(),
                    'grant_type' => 'fb_exchange_token',
                    'fb_exchange_token' => $this->getAccessToken(),
                        )
                );
            }
            catch (YNSFacebookApiException $e)
            {
                // most likely that user very recently revoked authorization.
                // In any event, we don't have an access token, so say so.
                return false;
            }

            if (empty($access_token_response))
            {
                return false;
            }

            $response_params = array();
            parse_str($access_token_response, $response_params);

            if (!isset($response_params['access_token']))
            {
                return false;
            }

            $this->destroySession();

            $this->setPersistentData(
                    'access_token', $response_params['access_token']
            );
        }

        /**
         * Determines the access token that should be used for API calls.
         * The first time this is called, $this->accessToken is set equal
         * to either a valid user access token, or it's set to the application
         * access token if a valid user access token wasn't available.  Subsequent
         * calls return whatever the first call returned.
         *
         * @return string The access token
         */
        public function getAccessToken()
        {
            if ($this->accessToken !== null)
            {
                // we've done this already and cached it.  Just return.
                return $this->accessToken;
            }

            // first establish access token to be the application
            // access token, in case we navigate to the /oauth/access_token
            // endpoint, where SOME access token is required.
			
            $this->setAccessToken($this->getApplicationAccessToken());
            $user_access_token = $this->getUserAccessToken();
            if ($user_access_token)
            {
                $this->setAccessToken($user_access_token);
            }

            return $this->accessToken;
        }

        /**
         * Determines and returns the user access token, first using
         * the signed request if present, and then falling back on
         * the authorization code if present.  The intent is to
         * return a valid user access token, or false if one is determined
         * to not be available.
         *
         * @return string A valid user access token, or false if one
         *                could not be determined.
         */
        public function getUserAccessToken()
        {
            // first, consider a signed request if it's supplied.
            // if there is a signed request, then it alone determines
            // the access token.
            $signed_request = $this->getSignedRequest();
            if ($signed_request)
            {
                // apps.facebook.com hands the access_token in the signed_request
                if (array_key_exists('oauth_token', $signed_request))
                {
                    $access_token = $signed_request['oauth_token'];
                    $this->setPersistentData('access_token', $access_token);
                    return $access_token;
                }

                // the JS SDK puts a code in with the redirect_uri of ''
                if (array_key_exists('code', $signed_request))
                {
                    $code = $signed_request['code'];
                    $access_token = $this->getAccessTokenFromCode($code, '');
                    if ($access_token)
                    {
                        $this->setPersistentData('code', $code);
                        $this->setPersistentData('access_token', $access_token);
                        return $access_token;
                    }
                }

                // signed request states there's no access token, so anything
                // stored should be cleared.
                $this->clearAllPersistentData();
                return false; // respect the signed request's data, even
                // if there's an authorization code or something else
            }

            $code = $this->getCode();
            if ($code && $code != $this->getPersistentData('code'))
            {
                $access_token = $this->getAccessTokenFromCode($code);
                if ($access_token)
                {
                    $this->setPersistentData('code', $code);
                    $this->setPersistentData('access_token', $access_token);
                    return $access_token;
                }

                // code was bogus, so everything based on it should be invalidated.
                $this->clearAllPersistentData();
                return false;
            }

            // as a fallback, just return whatever is in the persistent
            // store, knowing nothing explicit (signed request, authorization
            // code, etc.) was present to shadow it (or we saw a code in $_REQUEST,
            // but it's the same as what's in the persistent store)
            return $this->getPersistentData('access_token');
        }

        /**
         * Retrieve the signed request, either from a request parameter or,
         * if not present, from a cookie.
         *
         * @return string the signed request, if available, or null otherwise.
         */
        public function getSignedRequest()
        {
            if (!$this->signedRequest)
            {
                if (isset($_REQUEST['signed_request']))
                {
                    $this->signedRequest = $this->parseSignedRequest(
                            $_REQUEST['signed_request']);
                }
                else if (isset($_COOKIE[$this->getSignedRequestCookieName()]))
                {
                    $this->signedRequest = $this->parseSignedRequest(
                            $_COOKIE[$this->getSignedRequestCookieName()]);
                }
            }
            return $this->signedRequest;
        }

        /**
         * Get the UID of the connected user, or 0
         * if the Facebook user is not connected.
         *
         * @return string the UID if available.
         */
        public function getUser()
        {
            if ($this->user !== null)
            {
                // we've already determined this and cached the value.
                return $this->user;
            }

            return $this->user = $this->getUserFromAvailableData();
        }

        /**
         * Determines the connected user by first examining any signed
         * requests, then considering an authorization code, and then
         * falling back to any persistent store storing the user.
         *
         * @return integer The id of the connected Facebook user,
         *                 or 0 if no such user exists.
         */
        protected function getUserFromAvailableData()
        {
            // if a signed request is supplied, then it solely determines
            // who the user is.
            $signed_request = $this->getSignedRequest();
            if ($signed_request)
            {
                if (array_key_exists('user_id', $signed_request))
                {
                    $user = $signed_request['user_id'];
                    $this->setPersistentData('user_id', $signed_request['user_id']);
                    return $user;
                }

                // if the signed request didn't present a user id, then invalidate
                // all entries in any persistent store.
                $this->clearAllPersistentData();
                return 0;
            }

            $user = $this->getPersistentData('user_id', $default = 0);
            $persisted_access_token = $this->getPersistentData('access_token');

            // use access_token to fetch user id if we have a user access_token, or if
            // the cached access token has changed.
            $access_token = $this->getAccessToken();
            if ($access_token &&
                    $access_token != $this->getApplicationAccessToken() &&
                    !($user && $persisted_access_token == $access_token))
            {
                $user = $this->getUserFromAccessToken();
                if ($user)
                {
                    $this->setPersistentData('user_id', $user);
                }
                else
                {
                    $this->clearAllPersistentData();
                }
            }

            return $user;
        }

        /**
         * Get a Login URL for use with redirects. By default, full page redirect is
         * assumed. If you are using the generated URL with a window.open() call in
         * JavaScript, you can pass in display=popup as part of the $params.
         *
         * The parameters:
         * - redirect_uri: the url to go to after a successful login
         * - scope: comma separated list of requested extended perms
         *
         * @param array $params Provide custom parameters
         * @return string The URL for the login flow
         */
        public function getLoginUrl($params = array(), $redirect_url = '')
        {
            $this->establishCSRFTokenState();
			if (!$redirect_url) {
				$currentUrl = $this->getCurrentUrl();
			} else {
				$currentUrl = $redirect_url;
			}
            // if 'scope' is passed as an array, convert to comma separated list
            $scopeParams = isset($params['scope']) ? $params['scope'] : null;
            if ($scopeParams && is_array($scopeParams))
            {
                $params['scope'] = implode(',', $scopeParams);
            }

            return $this->getUrl(
                            'www', 'dialog/oauth', array_merge(array(
                                'client_id' => $this->getAppId(),
                                'redirect_uri' => $currentUrl, // possibly overwritten
                                'state' => $this->state), $params));
        }

        /**
         * Get a Logout URL suitable for use with redirects.
         *
         * The parameters:
         * - next: the url to go to after a successful logout
         *
         * @param array $params Provide custom parameters
         * @return string The URL for the logout flow
         */
        public function getLogoutUrl($params = array())
        {
            return $this->getUrl(
                            'www', 'logout.php', array_merge(array(
                                'next' => $this->getCurrentUrl(),
                                'access_token' => $this->getUserAccessToken(),
                                    ), $params)
            );
        }

        /**
         * Get a login status URL to fetch the status from Facebook.
         *
         * The parameters:
         * - ok_session: the URL to go to if a session is found
         * - no_session: the URL to go to if the user is not connected
         * - no_user: the URL to go to if the user is not signed into facebook
         *
         * @param array $params Provide custom parameters
         * @return string The URL for the logout flow
         */
        public function getLoginStatusUrl($params = array())
        {
            return $this->getUrl(
                            'www', 'extern/login_status.php', array_merge(array(
                                'api_key' => $this->getAppId(),
                                'no_session' => $this->getCurrentUrl(),
                                'no_user' => $this->getCurrentUrl(),
                                'ok_session' => $this->getCurrentUrl(),
                                'session_version' => 3,
                                    ), $params)
            );
        }

        /**
         * Make an API call.
         *
         * @return mixed The decoded response
         */
        public function api(/* polymorphic */)
        {
            $args = func_get_args();
            if (is_array($args[0]))
            {
                return $this->_restserver($args[0]);
            }
            else
            {
                return call_user_func_array(array($this, '_graph'), $args);
            }
        }

        /**
         * Constructs and returns the name of the cookie that
         * potentially houses the signed request for the app user.
         * The cookie is not set by the YNSBaseFacebook class, but
         * it may be set by the JavaScript SDK.
         *
         * @return string the name of the cookie that would house
         *         the signed request value.
         */
        protected function getSignedRequestCookieName()
        {
            return 'fbsr_' . $this->getAppId();
        }

        /**
         * Constructs and returns the name of the coookie that potentially contain
         * metadata. The cookie is not set by the YNSBaseFacebook class, but it may be
         * set by the JavaScript SDK.
         *
         * @return string the name of the cookie that would house metadata.
         */
        protected function getMetadataCookieName()
        {
            return 'fbm_' . $this->getAppId();
        }

        /**
         * Get the authorization code from the query parameters, if it exists,
         * and otherwise return false to signal no authorization code was
         * discoverable.
         *
         * @return mixed The authorization code, or false if the authorization
         *               code could not be determined.
         */
        protected function getCode()
        {
            if (isset($_REQUEST['code']))
            {
                if ($this->state !== null &&
                        isset($_REQUEST['state']) &&
                        $this->state === $_REQUEST['state'])
                {

                    // CSRF state has done its job, so clear it
                    $this->state = null;
                    $this->clearPersistentData('state');
                    return $_REQUEST['code'];
                }
                else
                {
                    self::errorLog('CSRF state token does not match one provided.');
                    return false;
                }
            }

            return false;
        }

        /**
         * Retrieves the UID with the understanding that
         * $this->accessToken has already been set and is
         * seemingly legitimate.  It relies on Facebook's Graph API
         * to retrieve user information and then extract
         * the user ID.
         *
         * @return integer Returns the UID of the Facebook user, or 0
         *                 if the Facebook user could not be determined.
         */
        protected function getUserFromAccessToken()
        {
            try
            {
                $user_info = $this->api('/me');
                return $user_info['id'];
            }
            catch (YNSFacebookApiException $e)
            {
                return 0;
            }
        }

        /**
         * Returns the access token that should be used for logged out
         * users when no authorization code is available.
         *
         * @return string The application access token, useful for gathering
         *                public information about users and applications.
         */
        protected function getApplicationAccessToken()
        {
            return $this->appId . '|' . $this->appSecret;
        }

        /**
         * Lays down a CSRF state token for this process.
         *
         * @return void
         */
        protected function establishCSRFTokenState()
        {
            if ($this->state === null)
            {
                $this->state = md5(uniqid(mt_rand(), true));
                $this->setPersistentData('state', $this->state);
            }
        }

        /**
         * Retrieves an access token for the given authorization code
         * (previously generated from www.facebook.com on behalf of
         * a specific user).  The authorization code is sent to graph.facebook.com
         * and a legitimate access token is generated provided the access token
         * and the user for which it was generated all match, and the user is
         * either logged in to Facebook or has granted an offline access permission.
         *
         * @param string $code An authorization code.
         * @return mixed An access token exchanged for the authorization code, or
         *               false if an access token could not be generated.
         */
        protected function getAccessTokenFromCode($code, $redirect_uri = null)
        {
            if (empty($code))
            {
                return false;
            }

            if ($redirect_uri === null)
            {
                $redirect_uri = $this->getCurrentUrl();
            }

            try
            {
                // need to circumvent json_decode by calling _oauthRequest
                // directly, since response isn't JSON format.
                $access_token_response =
                        $this->_oauthRequest(
                        $this->getUrl('graph', '/oauth/access_token'), $params = array('client_id' => $this->getAppId(),
                    'client_secret' => $this->getAppSecret(),
                    'redirect_uri' => $redirect_uri,
                    'code' => $code));
            }
            catch (YNSFacebookApiException $e)
            {
                // most likely that user very recently revoked authorization.
                // In any event, we don't have an access token, so say so.
                return false;
            }

            if (empty($access_token_response))
            {
                return false;
            }

            $response_params = array();
            parse_str($access_token_response, $response_params);
            if (!isset($response_params['access_token']))
            {
                return false;
            }

            return $response_params['access_token'];
        }

        /**
         * Invoke the old restserver.php endpoint.
         *
         * @param array $params Method call object
         *
         * @return mixed The decoded response object
         * @throws YNSFacebookApiException
         */
        protected function _restserver($params)
        {
            // generic application level parameters
            $params['api_key'] = $this->getAppId();
            $params['format'] = 'json-strings';

            $result = json_decode($this->_oauthRequest(
                            $this->getApiUrl($params['method']), $params
                    ), true);

            // results are returned, errors are thrown
            if (is_array($result) && isset($result['error_code']))
            {
                $this->throwAPIException($result);
                // @codeCoverageIgnoreStart
            }
            // @codeCoverageIgnoreEnd

            $method = strtolower($params['method']);
            if ($method === 'auth.expiresession' ||
                    $method === 'auth.revokeauthorization')
            {
                $this->destroySession();
            }

            return $result;
        }

        /**
         * Return true if this is video post.
         *
         * @param string $path The path
         * @param string $method The http method (default 'GET')
         *
         * @return boolean true if this is video post
         */
        protected function isVideoPost($path, $method = 'GET')
        {
            if ($method == 'POST' && preg_match("/^(\/)(.+)(\/)(videos)$/", $path))
            {
                return true;
            }
            return false;
        }

        /**
         * Invoke the Graph API.
         *
         * @param string $path The path (required)
         * @param string $method The http method (default 'GET')
         * @param array $params The query/post data
         *
         * @return mixed The decoded response object
         * @throws YNSFacebookApiException
         */
        protected function _graph($path, $method = 'GET', $params = array())
        {
            if (is_array($method) && empty($params))
            {
                $params = $method;
                $method = 'GET';
            }
            $params['method'] = $method; // method override as we always do a POST

            if ($this->isVideoPost($path, $method))
            {
                $domainKey = 'graph_video';
            }
            else
            {
                $domainKey = 'graph';
            }

            $result = json_decode($this->_oauthRequest(
                            $this->getUrl($domainKey, $path), $params
                    ), true);

            // results are returned, errors are thrown
            if (is_array($result) && isset($result['error']))
            {
                $this->throwAPIException($result);
                // @codeCoverageIgnoreStart
            }
            // @codeCoverageIgnoreEnd

            return $result;
        }

        /**
         * Make a OAuth Request.
         *
         * @param string $url The path (required)
         * @param array $params The query/post data
         *
         * @return string The decoded response object
         * @throws YNSFacebookApiException
         */
        protected function _oauthRequest($url, $params)
        {
            if (!isset($params['access_token']))
            {
                $params['access_token'] = $this->getAccessToken();
            }

            // json_encode all params values that are not strings
            foreach ($params as $key => $value)
            {
                if (!is_string($value))
                {
                    $params[$key] = json_encode($value);
                }
            }

            return $this->makeRequest($url, $params);
        }

        /**
         * Makes an HTTP request. This method can be overridden by subclasses if
         * developers want to do fancier things or use something other than curl to
         * make the request.
         *
         * @param string $url The URL to make the request to
         * @param array $params The parameters to use for the POST body
         * @param CurlHandler $ch Initialized curl handle
         *
         * @return string The response text
         */
        protected function makeRequest($url, $params, $ch = null)
        {
            if (!$ch)
            {
                $ch = curl_init();
            }

            $opts = self::$CURL_OPTS;
            if ($this->getFileUploadSupport())
            {
                $opts[CURLOPT_POSTFIELDS] = $params;
            }
            else
            {
                $opts[CURLOPT_POSTFIELDS] = http_build_query($params, null, '&');
            }
            $opts[CURLOPT_URL] = $url;

            // disable the 'Expect: 100-continue' behaviour. This causes CURL to wait
            // for 2 seconds if the server does not support this header.
            if (isset($opts[CURLOPT_HTTPHEADER]))
            {
                $existing_headers = $opts[CURLOPT_HTTPHEADER];
                $existing_headers[] = 'Expect:';
                $opts[CURLOPT_HTTPHEADER] = $existing_headers;
            }
            else
            {
                $opts[CURLOPT_HTTPHEADER] = array('Expect:');
            }

            curl_setopt_array($ch, $opts);
            $result = curl_exec($ch);

            if (curl_errno($ch) == 60)
            { // CURLE_SSL_CACERT
                self::errorLog('Invalid or no certificate authority found, ' .
                        'using bundled information');
                curl_setopt($ch, CURLOPT_CAINFO, dirname(__FILE__) . '/fb_ca_chain_bundle.crt');
                $result = curl_exec($ch);
            }

            // With dual stacked DNS responses, it's possible for a server to
            // have IPv6 enabled but not have IPv6 connectivity.  If this is
            // the case, curl will try IPv4 first and if that fails, then it will
            // fall back to IPv6 and the error EHOSTUNREACH is returned by the
            // operating system.
            if ($result === false && empty($opts[CURLOPT_IPRESOLVE]))
            {
                $matches = array();
                $regex = '/Failed to connect to ([^:].*): Network is unreachable/';
                if (preg_match($regex, curl_error($ch), $matches))
                {
                    if (strlen(@inet_pton($matches[1])) === 16)
                    {
                        self::errorLog('Invalid IPv6 configuration on server, ' .
                                'Please disable or get native IPv6 on your server.');
                        self::$CURL_OPTS[CURLOPT_IPRESOLVE] = CURL_IPRESOLVE_V4;
                        curl_setopt($ch, CURLOPT_IPRESOLVE, CURL_IPRESOLVE_V4);
                        $result = curl_exec($ch);
                    }
                }
            }

            if ($result === false)
            {
                $e = new YNSFacebookApiException(array(
                            'error_code' => curl_errno($ch),
                            'error' => array(
                                'message' => curl_error($ch),
                                'type' => 'CurlException',
                            ),
                        ));
                curl_close($ch);
                throw $e;
            }
            curl_close($ch);
            return $result;
        }

        /**
         * Parses a signed_request and validates the signature.
         *
         * @param string $signed_request A signed token
         * @return array The payload inside it or null if the sig is wrong
         */
        protected function parseSignedRequest($signed_request)
        {
            list($encoded_sig, $payload) = explode('.', $signed_request, 2);

            // decode the data
            $sig = self::base64UrlDecode($encoded_sig);
            $data = json_decode(self::base64UrlDecode($payload), true);

            if (strtoupper($data['algorithm']) !== self::SIGNED_REQUEST_ALGORITHM)
            {
                self::errorLog(
                        'Unknown algorithm. Expected ' . self::SIGNED_REQUEST_ALGORITHM);
                return null;
            }

            // check sig
            $expected_sig = hash_hmac('sha256', $payload, $this->getAppSecret(), $raw = true);
            if ($sig !== $expected_sig)
            {
                self::errorLog('Bad Signed JSON signature!');
                return null;
            }

            return $data;
        }

        /**
         * Makes a signed_request blob using the given data.
         *
         * @param array The data array.
         * @return string The signed request.
         */
        protected function makeSignedRequest($data)
        {
            if (!is_array($data))
            {
                throw new InvalidArgumentException(
                        'makeSignedRequest expects an array. Got: ' . print_r($data, true));
            }
            $data['algorithm'] = self::SIGNED_REQUEST_ALGORITHM;
            $data['issued_at'] = time();
            $json = json_encode($data);
            $b64 = self::base64UrlEncode($json);
            $raw_sig = hash_hmac('sha256', $b64, $this->getAppSecret(), $raw = true);
            $sig = self::base64UrlEncode($raw_sig);
            return $sig . '.' . $b64;
        }

        /**
         * Build the URL for api given parameters.
         *
         * @param $method String the method name.
         * @return string The URL for the given parameters
         */
        protected function getApiUrl($method)
        {
            static $READ_ONLY_CALLS =
            array('admin.getallocation' => 1,
                'admin.getappproperties' => 1,
                'admin.getbannedusers' => 1,
                'admin.getlivestreamvialink' => 1,
                'admin.getmetrics' => 1,
                'admin.getrestrictioninfo' => 1,
                'application.getpublicinfo' => 1,
                'auth.getapppublickey' => 1,
                'auth.getsession' => 1,
                'auth.getsignedpublicsessiondata' => 1,
                'comments.get' => 1,
                'connect.getunconnectedfriendscount' => 1,
                'dashboard.getactivity' => 1,
                'dashboard.getcount' => 1,
                'dashboard.getglobalnews' => 1,
                'dashboard.getnews' => 1,
                'dashboard.multigetcount' => 1,
                'dashboard.multigetnews' => 1,
                'data.getcookies' => 1,
                'events.get' => 1,
                'events.getmembers' => 1,
                'fbml.getcustomtags' => 1,
                'feed.getappfriendstories' => 1,
                'feed.getregisteredtemplatebundlebyid' => 1,
                'feed.getregisteredtemplatebundles' => 1,
                'fql.multiquery' => 1,
                'fql.query' => 1,
                'friends.arefriends' => 1,
                'friends.get' => 1,
                'friends.getappusers' => 1,
                'friends.getlists' => 1,
                'friends.getmutualfriends' => 1,
                'gifts.get' => 1,
                'groups.get' => 1,
                'groups.getmembers' => 1,
                'intl.gettranslations' => 1,
                'links.get' => 1,
                'notes.get' => 1,
                'notifications.get' => 1,
                'pages.getinfo' => 1,
                'pages.isadmin' => 1,
                'pages.isappadded' => 1,
                'pages.isfan' => 1,
                'permissions.checkavailableapiaccess' => 1,
                'permissions.checkgrantedapiaccess' => 1,
                'photos.get' => 1,
                'photos.getalbums' => 1,
                'photos.gettags' => 1,
                'profile.getinfo' => 1,
                'profile.getinfooptions' => 1,
                'stream.get' => 1,
                'stream.getcomments' => 1,
                'stream.getfilters' => 1,
                'users.getinfo' => 1,
                'users.getloggedinuser' => 1,
                'users.getstandardinfo' => 1,
                'users.hasapppermission' => 1,
                'users.isappuser' => 1,
                'users.isverified' => 1,
                'video.getuploadlimits' => 1);
            $name = 'api';
            if (isset($READ_ONLY_CALLS[strtolower($method)]))
            {
                $name = 'api_read';
            }
            else if (strtolower($method) == 'video.upload')
            {
                $name = 'api_video';
            }
            return self::getUrl($name, 'restserver.php');
        }

        /**
         * Build the URL for given domain alias, path and parameters.
         *
         * @param $name string The name of the domain
         * @param $path string Optional path (without a leading slash)
         * @param $params array Optional query parameters
         *
         * @return string The URL for the given parameters
         */
        protected function getUrl($name, $path = '', $params = array())
        {
            $url = self::$DOMAIN_MAP[$name];
            if ($path)
            {
                if ($path[0] === '/')
                {
                    $path = substr($path, 1);
                }
                $url .= $path;
            }
            if ($params)
            {
                $url .= '?' . http_build_query($params, null, '&');
            }

            return $url;
        }

        protected function getHttpHost()
        {
            if ($this->trustForwarded && isset($_SERVER['HTTP_X_FORWARDED_HOST']))
            {
                return $_SERVER['HTTP_X_FORWARDED_HOST'];
            }
            return $_SERVER['HTTP_HOST'];
        }

        protected function getHttpProtocol()
        {
            if ($this->trustForwarded && isset($_SERVER['HTTP_X_FORWARDED_PROTO']))
            {
                if ($_SERVER['HTTP_X_FORWARDED_PROTO'] === 'https')
                {
                    return 'https';
                }
                return 'http';
            }
            if (isset($_SERVER['HTTPS']) &&
                    ($_SERVER['HTTPS'] === 'on' || $_SERVER['HTTPS'] == 1))
            {
                return 'https';
            }
            return 'http';
        }

        /**
         * Get the base domain used for the cookie.
         */
        protected function getBaseDomain()
        {
            // The base domain is stored in the metadata cookie if not we fallback
            // to the current hostname
            $metadata = $this->getMetadataCookie();
            if (array_key_exists('base_domain', $metadata) &&
                    !empty($metadata['base_domain']))
            {
                return trim($metadata['base_domain'], '.');
            }
            return $this->getHttpHost();
        }

        /**

          /**
         * Returns the Current URL, stripping it of known FB parameters that should
         * not persist.
         *
         * @return string The current URL
         */
        protected function getCurrentUrl()
        {
            $protocol = $this->getHttpProtocol() . '://';
            $host = $this->getHttpHost();
            $currentUrl = $protocol . $host . $_SERVER['REQUEST_URI'];
            $parts = parse_url($currentUrl);

            $query = '';
            if (!empty($parts['query']))
            {
                // drop known fb params
                $params = explode('&', $parts['query']);
                $retained_params = array();
                foreach ($params as $param)
                {
                    if ($this->shouldRetainParam($param))
                    {
                        $retained_params[] = $param;
                    }
                }

                if (!empty($retained_params))
                {
                    $query = '?' . implode($retained_params, '&');
                }
            }

            // use port if non default
            $port =
                    isset($parts['port']) &&
                    (($protocol === 'http://' && $parts['port'] !== 80) ||
                    ($protocol === 'https://' && $parts['port'] !== 443)) ? ':' . $parts['port'] : '';

            // rebuild
            return $protocol . $parts['host'] . $port . $parts['path'] . $query;
        }

        /**
         * Returns true if and only if the key or key/value pair should
         * be retained as part of the query string.  This amounts to
         * a brute-force search of the very small list of Facebook-specific
         * params that should be stripped out.
         *
         * @param string $param A key or key/value pair within a URL's query (e.g.
         *                     'foo=a', 'foo=', or 'foo'.
         *
         * @return boolean
         */
        protected function shouldRetainParam($param)
        {
            foreach (self::$DROP_QUERY_PARAMS as $drop_query_param)
            {
                if (strpos($param, $drop_query_param . '=') === 0)
                {
                    return false;
                }
            }

            return true;
        }

        /**
         * Analyzes the supplied result to see if it was thrown
         * because the access token is no longer valid.  If that is
         * the case, then we destroy the session.
         *
         * @param $result array A record storing the error message returned
         *                      by a failed API call.
         */
        protected function throwAPIException($result)
        {
            $e = new YNSFacebookApiException($result);
            switch ($e->getType())
            {
                // OAuth 2.0 Draft 00 style
                case 'OAuthException':
                // OAuth 2.0 Draft 10 style
                case 'invalid_token':
                // REST server errors are just Exceptions
                case 'Exception':
                    $message = $e->getMessage();
                    if ((strpos($message, 'Error validating access token') !== false) ||
                            (strpos($message, 'Invalid OAuth access token') !== false) ||
                            (strpos($message, 'An active access token must be used') !== false)
                    )
                    {
                        $this->destroySession();
                    }
                    break;
            }

            throw $e;
        }

        /**
         * Prints to the error log if you aren't in command line mode.
         *
         * @param string $msg Log message
         */
        protected static function errorLog($msg)
        {
            // disable error log if we are running in a CLI environment
            // @codeCoverageIgnoreStart
            if (php_sapi_name() != 'cli')
            {
                error_log($msg);
            }
            // uncomment this if you want to see the errors on the page
            // print 'error_log: '.$msg."\n";
            // @codeCoverageIgnoreEnd
        }

        /**
         * Base64 encoding that doesn't need to be urlencode()ed.
         * Exactly the same as base64_encode except it uses
         *   - instead of +
         *   _ instead of /
         *   No padded =
         *
         * @param string $input base64UrlEncoded string
         * @return string
         */
        protected static function base64UrlDecode($input)
        {
            return base64_decode(strtr($input, '-_', '+/'));
        }

        /**
         * Base64 encoding that doesn't need to be urlencode()ed.
         * Exactly the same as base64_encode except it uses
         *   - instead of +
         *   _ instead of /
         *
         * @param string $input string
         * @return string base64Url encoded string
         */
        protected static function base64UrlEncode($input)
        {
            $str = strtr(base64_encode($input), '+/', '-_');
            $str = str_replace('=', '', $str);
            return $str;
        }

        /**
         * Destroy the current session
         */
        public function destroySession()
        {
            $this->accessToken = null;
            $this->signedRequest = null;
            $this->user = null;
            $this->clearAllPersistentData();

            // Javascript sets a cookie that will be used in getSignedRequest that we
            // need to clear if we can
            $cookie_name = $this->getSignedRequestCookieName();
            if (array_key_exists($cookie_name, $_COOKIE))
            {
                unset($_COOKIE[$cookie_name]);
                if (!headers_sent())
                {
                    $base_domain = $this->getBaseDomain();
                    setcookie($cookie_name, '', 1, '/', '.' . $base_domain);
                }
                else
                {
                    // @codeCoverageIgnoreStart
                    self::errorLog(
                            'There exists a cookie that we wanted to clear that we couldn\'t ' .
                            'clear because headers was already sent. Make sure to do the first ' .
                            'API call before outputing anything.'
                    );
                    // @codeCoverageIgnoreEnd
                }
            }
        }

        /**
         * Parses the metadata cookie that our Javascript API set
         *
         * @return  an array mapping key to value
         */
        protected function getMetadataCookie()
        {
            $cookie_name = $this->getMetadataCookieName();
            if (!array_key_exists($cookie_name, $_COOKIE))
            {
                return array();
            }

            // The cookie value can be wrapped in "-characters so remove them
            $cookie_value = trim($_COOKIE[$cookie_name], '"');

            if (empty($cookie_value))
            {
                return array();
            }

            $parts = explode('&', $cookie_value);
            $metadata = array();
            foreach ($parts as $part)
            {
                $pair = explode('=', $part, 2);
                if (!empty($pair[0]))
                {
                    $metadata[urldecode($pair[0])] =
                            (count($pair) > 1) ? urldecode($pair[1]) : '';
                }
            }

            return $metadata;
        }

        protected static function isAllowedDomain($big, $small)
        {
            if ($big === $small)
            {
                return true;
            }
            return self::endsWith($big, '.' . $small);
        }

        protected static function endsWith($big, $small)
        {
            $len = strlen($small);
            if ($len === 0)
            {
                return true;
            }
            return substr($big, -$len) === $small;
        }

        /**
         * Each of the following four methods should be overridden in
         * a concrete subclass, as they are in the provided Facebook class.
         * The Facebook class uses PHP sessions to provide a primitive
         * persistent store, but another subclass--one that you implement--
         * might use a database, memcache, or an in-memory cache.
         *
         * @see Facebook
         */

        /**
         * Stores the given ($key, $value) pair, so that future calls to
         * getPersistentData($key) return $value. This call may be in another request.
         *
         * @param string $key
         * @param array $value
         *
         * @return void
         */
        abstract protected function setPersistentData($key, $value);

        /**
         * Get the data for $key, persisted by YNSBaseFacebook::setPersistentData()
         *
         * @param string $key The key of the data to retrieve
         * @param boolean $default The default value to return if $key is not found
         *
         * @return mixed
         */
        abstract protected function getPersistentData($key, $default = false);

        /**
         * Clear the data with $key from the persistent storage
         *
         * @param string $key
         * @return void
         */
        abstract protected function clearPersistentData($key);

        /**
         * Clear all data from the persistent storage
         *
         * @return void
         */
        abstract protected function clearAllPersistentData();
    }

}

/**
 * Extends the YNSBaseFacebook class with the intent of using
 * PHP sessions to store user ids and access tokens.
 */
if (!class_exists("FacebookSBYN"))
{

    class FacebookSBYN extends YNSBaseFacebook
    {

        const FBSS_COOKIE_NAME = 'fbss';

        // We can set this to a high number because the main session
        // expiration will trump this.
        const FBSS_COOKIE_EXPIRE = 31556926; // 1 year

        // Stores the shared session ID if one is set.

        protected $sharedSessionID;

        /**
         * Identical to the parent constructor, except that
         * we start a PHP session to store the user ID and
         * access token if during the course of execution
         * we discover them.
         *
         * @param Array $config the application configuration. Additionally
         * accepts "sharedSession" as a boolean to turn on a secondary
         * cookie for environments with a shared session (that is, your app
         * shares the domain with other apps).
         * @see YNSBaseFacebook::__construct in facebook.php
         */
        public function __construct($config)
        {
            if (isset($config['app_id']))
            {
                $config['appId'] = $config['app_id'];
            }
            if (!session_id())
            {
                session_start();
            }
            parent::__construct($config);
            if (!empty($config['sharedSession']))
            {
                $this->initSharedSession();
            }
        }

        protected static $kSupportedKeys =
                array('state', 'code', 'access_token', 'user_id');

        
		public function getSession()
		{
			return $this->getAccessToken();
		}
		
		public function setSession($aSession)
		{
			return $this->setAccessToken($aSession);
		}		
		
		protected function initSharedSession()
        {
            $cookie_name = $this->getSharedSessionCookieName();
            if (isset($_COOKIE[$cookie_name]))
            {
                $data = $this->parseSignedRequest($_COOKIE[$cookie_name]);
                if ($data && !empty($data['domain']) &&
                        self::isAllowedDomain($this->getHttpHost(), $data['domain']))
                {
                    // good case
                    $this->sharedSessionID = $data['id'];
                    return;
                }
                // ignoring potentially unreachable data
            }
            // evil/corrupt/missing case
            $base_domain = $this->getBaseDomain();
            $this->sharedSessionID = md5(uniqid(mt_rand(), true));
            $cookie_value = $this->makeSignedRequest(
                    array(
                        'domain' => $base_domain,
                        'id' => $this->sharedSessionID,
                    )
            );
            $_COOKIE[$cookie_name] = $cookie_value;
            if (!headers_sent())
            {
                $expire = time() + self::FBSS_COOKIE_EXPIRE;
                setcookie($cookie_name, $cookie_value, $expire, '/', '.' . $base_domain);
            }
            else
            {
                // @codeCoverageIgnoreStart
                self::errorLog(
                        'Shared session ID cookie could not be set! You must ensure you ' .
                        'create the Facebook instance before headers have been sent. This ' .
                        'will cause authentication issues after the first request.'
                );
                // @codeCoverageIgnoreEnd
            }
        }

        /**
         * Provides the implementations of the inherited abstract
         * methods.  The implementation uses PHP sessions to maintain
         * a store for authorization codes, user ids, CSRF states, and
         * access tokens.
         */
        protected function setPersistentData($key, $value)
        {
            if (!in_array($key, self::$kSupportedKeys))
            {
                self::errorLog('Unsupported key passed to setPersistentData.');
                return;
            }

            $session_var_name = $this->constructSessionVariableName($key);
            $_SESSION[$session_var_name] = $value;
        }

        protected function getPersistentData($key, $default = false)
        {
            if (!in_array($key, self::$kSupportedKeys))
            {
                self::errorLog('Unsupported key passed to getPersistentData.');
                return $default;
            }

            $session_var_name = $this->constructSessionVariableName($key);
            return isset($_SESSION[$session_var_name]) ?
                    $_SESSION[$session_var_name] : $default;
        }

        protected function clearPersistentData($key)
        {
            if (!in_array($key, self::$kSupportedKeys))
            {
                self::errorLog('Unsupported key passed to clearPersistentData.');
                return;
            }

            $session_var_name = $this->constructSessionVariableName($key);
            unset($_SESSION[$session_var_name]);
        }

        protected function clearAllPersistentData()
        {
            foreach (self::$kSupportedKeys as $key)
            {
                $this->clearPersistentData($key);
            }
            if ($this->sharedSessionID)
            {
                $this->deleteSharedSessionCookie();
            }
        }

        protected function deleteSharedSessionCookie()
        {
            $cookie_name = $this->getSharedSessionCookieName();
            unset($_COOKIE[$cookie_name]);
            $base_domain = $this->getBaseDomain();
            setcookie($cookie_name, '', 1, '/', '.' . $base_domain);
        }

        protected function getSharedSessionCookieName()
        {
            return self::FBSS_COOKIE_NAME . '_' . $this->getAppId();
        }

        protected function constructSessionVariableName($key)
        {
            $parts = array('fb', $this->getAppId(), $key);
            if ($this->sharedSessionID)
            {
                array_unshift($parts, $this->sharedSessionID);
            }
            return implode('_', $parts);
        }

    }

}